A significant portion of the defense spend is STEM. It takes a lot of engineering to build a bomb. It takes a lot of math to create/break encryption....
The US could be safe spending 1% of its GDP on defense and largely importing foreign weapon system designs for local manufacturing. There’s clearly a lower limit, but half of current spending is perfectly reasonable starting point before decisions get tricky.
I'm pretty sure they legally can't "largely import foreign weapon designs". The Berry and Kissel amendments, not to mention ITAR and a few other regulations, put a strong incentive on in-sourcing when at all possible. The only exceptions are for things that are really hard to get domestically.
I can’t tell if you’re unsure of basic civics, or if you’re implying something deeper.
You need to have local know-how from the ground up.
(I wish Thermal and Night Vision was cheaper)
I was just looking it up the other day and the first wireless time system was implemented by US and French defensive systems.
GPS, the Internet, etc... DARPA projects alone are impressive. https://wikipedia.org/wiki/DARPA#Projects
I do miss those private research groups like Bell Labs and Xerox PARC though.
NASA does a lot of good work too, and there are some really cool space projects there that need more funding.
Packet switching saw first implementation outside the US including some key ideas like a router. We ended up with the ARPANET > Internet story everyone is familiar with more as an accident of history and a dash of propaganda rather than something that required US military participation. https://en.wikipedia.org/wiki/NPL_network
Teflon is another one people bring up as coming from the military but was invented accidentally outside the military long before its use in the Manhattan Project.